Boron removal from landfill leachate by means of nanofiltration and reverse osmosis

The removal of boron from chemical landfill leachate, of 25.4 +/- 0.7 mg/L boron content, by means of nanofiltration and reverse osmosis was investigated. The BW-30, TW-30, NF-90 and NF-45 (Filmtec) membranes, working at maximum permissible operating pressure were applied. Our experimental results indicated that boron rejection mostly depends on membrane type and leachate pH level while it is almost recovery independent. The more detailed analysis of abovementioned results showed that boron can be effectively removed only at a shifted feedwater pH, close to 11, that is the highest value for long term operation of RO membranes. The highest boron rejection (close to 99%), and the low enough permeate boron content (< 1 ppm) were observed in the case of the BW-30 membrane up to 50% recovery only. Thus a two stage RO system, operated under alkaline conditions was proposed to efficiently remove the boron from such leachate.